In the traditional technique for obturating a root canal, strand-like pieces of a thermoplastic material, known as points, are inserted into a prepared or stripped root canal. Typically, gutta percha is employed as the point and these points are physically compacted by small manually actuated instruments known as "plungers" and "spreaders", or by machine driven "compactors". Another technique involves the use of a rigid carrier member that is coated with a thermoplastic material, such as gutta percha, inserted into the prepared root canal and then broken off, leaving a segment of the carrier and the coating within the root canal.
This procedure was first described in the Journal of Endodontics, Vol. 4, No. 6, pp. 184-88, June, 1978. It taught that a file can be utilized as the rigid carrier. The last file employed to instrument the canal is notched so that it will break away within the canal. It is then coated with sufficient gutta percha for obturation of the root canal, the gutta percha being heated sufficiently in an open flame to permit molding of the coating on the file with the fingers. The coated file is then inserted into the canal and broken off, as described hereinabove.
The author of this publication is also the patentee of several U.S. patents, including U.S. Pat. Nos. 4,758,156 and 4,894,011. While both are broadly directed toward the use of coated files, the elder patent features a rigid carrier tool that is provided with a distal end configuration that will resist rotation of the tool within the canal, thereby aiding breaking and removal of the proximal portion. Additionally, the shaft of the tool is provided with a reduced torque area to aid controlled breakage.
The latter patent further enhances the carrier member by providing a spiral groove along the distal portion to achieve the augering action, while resisting drilling. Rather significantly, the patent specifically states that the prior art teaching of a file as the carrier does have limitations which are overcome by the spiral groove construction.
Notwithstanding the usefulness of this technique for employing coated files and other rigid carrier tools, the foregoing patents and publication do not disclose any means for applying the coating other than manually and with heating over a flame. The present invention eliminates the need for manual manipulation, as well as any contact with the obturating material prior to placement within the root canal.